In recent years, it has been proved that tea is effective in maintaining health, and attention has been paid to the medicinal properties of tea. In particular, tea contains, for example, catechins having an oncogenic suppression activity and an antibacterial activity, carotene having an oncogenic suppression activity, and vitamin E having an antioxidant activity and a senescence suppression activity.
However, with sencha, medium-grade green tea made by decocting tea leaves in a teapot, vitamin E, carotene, dietary fiber and other components of the tea leaves do not dissolve into hot water. Furthermore, with respect to catechins, only about 23% of the entire amount of catechins contained in the tea leaves dissolves, and most of these components remain undissolved in used tea leaves, which are discarded.
On the other hand, matcha made by processing tea leaves into fine powder is a form of drink that allows for intake of 100% of the components of the tea leaves. However, matcha is in most cases drunk in the field of tea ceremony and is not commonly drunk. The tea ceremony is also a kind of art that values the rules of behavior and requires appropriate tea equipment accordingly. Therefore, matcha cannot be drunk as conveniently as medium-grade green tea.
Thus, in recent years, matcha filled in capsules is sold as supplements (dietary supplements). Patent Document 1 discloses a device (tabletop stirrer) for dissolving a water-soluble capsule so that matcha filled in the water-soluble capsule can be drunk conveniently.
However, the tabletop stirrer of Patent Document 1 aims at crushing and dissolving a capsule manually using hot water. Therefore, for example, it takes much time to crush and dissolve a capsule using cold water during the hot summer season. Furthermore, to make tea for several people at one time, it is necessary to crush and dissolve a plurality of capsules at one time, and hence there is a problem in that a considerably long time is required when a manual stirrer is used. Moreover, even when the tabletop stirrer of Patent Document 1 is applied to an electrically driven type as it is, in the case of an electrically-driven stirrer rotating at a constant speed, its structure causes a phenomenon in which the capsule is caught in the space between the stirring blades. Therefore, the capsule cannot be crushed and dissolved.
Moreover, electric stirring and foaming tools for coffee are commercially available. Such a tool has a stirring portion formed of a coil that is processed into a doughnut shape. When such a tool is used to perform stirring and foaming, if the tool is inserted upright into a vessel from above and rotated, a vortex having a hollow central portion is generated, which makes it difficult to form foam effectively. Therefore, in order to form foam effectively, a tricky operation of, for example, tilting the tool to various angles or moving the tool in all directions is necessary. There also is a problem in that an incorrect operation results in the splashing of droplets to the outside of the vessel.
Generally, if a rotating body is rapidly rotated underwater at a constant speed, a V-shaped vortex is formed by centrifugal forces, and a cavity is generated around the rotating shaft. It is inefficient to provide the rotating shaft with a structure that can act on flotages in water. The water flow forming a vortex is a horizontally rotating water flow except for the time when the vortex is initially formed. Therefore, energy that moves the flotages vertically is not generated. Thus, the occurrence of a V-shaped vortex due to high-speed rotation is a disadvantageous phenomenon in crushing and dissolving the flotages and forming foam by stirring.
Even if a rotating body that is capable of pumping without generating a V-shaped vortex could be realized, the flotages could possibly not be carried by the flow of pumped water depending on the tip shape of the rotating body. That is to say, if the tip of the rotating body has a horizontal plane or if a horizontal plane is formed at a tip portion of the rotating body as a result of rotation, when the rotating body is rotated, the flotages are adsorbed to a bottom surface of the rotating body, rotate in horizontal direction together with the rotating body, and do not move upward.
For example, some types of submersible pumps are capable of pumping by rotating propeller blades (submersible propeller pumps). However, even though such pumps are capable of pumping, when the propeller blades are rotated, a horizontal rotating water flow is generated in the plane of rotation. Therefore, there is the disadvantage that flotages that are elongated but has a length greater than the distance between respective blades constituting the propeller cannot be carried by the flow of pumped water.
Thus, if a stirrer that is capable of allowing flotages to be carried by a flow of pumped water without generating a V-shaped vortex even when rapidly rotating and, furthermore, that can perform stirring efficiently without causing droplets to splash onto a surrounding area is provided, water-soluble capsules can be efficiently crushed and dissolved not only in hot water but also in cold water. Since even a plurality of capsules can be crushed and dissolved in a short period of time, tea or the like can be served to a plurality of people at one time. Moreover, powdered tea leaves such as matcha can be stirred and foamed conveniently and enjoyed in all seasons of the year. Furthermore, in addition to the enjoyment of various kinds of tea, it also is possible to enjoy making dressings using oil, vinegar, mayonnaise, ketchup, and the like.
Patent Document 1: Japanese Patent No. 3803357